DNA damage occurs throughout life from a variety of sources, and it is
imperative to repair damage in a timely manner to maintain genome
stability. Thus, DNA repair mechanisms are a fundamental part of life.
Nucleotide Excision Repair (NER) plays an important role in the removal
of bulky DNA adducts, such as cyclobutane pyrimidine dimers (CPDs) from
ultraviolet (UV) light or DNA crosslinking damage from platinum-based
chemotherapeutics, such as cisplatin. A main component for the NER
pathway is transcription factor IIH (TFIIH), a multifunctional,
10-subunit protein complex with crucial roles in both transcription and
NER. In transcription, TFIIH is a component of the pre-initiation
complex (PIC) and is important for promoter opening and the
phosphorylation of RNA Polymerase II (RNA Pol II). During repair, TFIIH
is important for DNA unwinding, recruitment of downstream repair
factors, and verification of the bulky lesion. Several different disease
states can arise from mutations within subunits of the TFIIH complex.
Most strikingly are Xeroderma Pigmentosum (XP), XP combined with
Cockayne Syndrome (CS), and Trichothiodystrophy (TTD). Here, we
summarize the recruitment and functions of TFIIH in the two NER
subpathways, global genomic (GG-NER) and transcription-coupled NER
(TC-NER). We will also discuss how TFIIH’s roles in the two subpathways
lead to different genetic disorders.